Night Skies of July over Tanzania

July Night Skies over Tanzania

After several years of quiet with a “deep minimum” in 2009 in its 11-year cycle, the Sun is now waking up, with colossal energies breaking through the surface in areas seen from the Earth as SUNSPOTS.

If you were lucky to witness the recent event of century, the “Transit of Venus” on June 6, and saw the tiny dot of Venus crossing the face of the Sun, then you can you will also be able to see the sunspots, which can be nearly six times bigger than that dot of Venus.

The dark spots on the Sun can be seen during the daytime using a pair of solar glasses or by projecting the image of the Sun through a simple telescope, such as a Galileoscope, or through a pinhole. The pictures show the setup of the Galieoscope, the sunspots that I viewed, and picture from the NASA website www.spaceweather.com for comparison. Note that the Galileoscope image is inverted by the telescope lenses.

Sunspots are huge areas (up to 100,000 km across) on the surface of the Sun that are about 2,000 degrees centigrade cooler than the rest of the Sun’s surface, which is around 6,000 degrees centigrade. Objects heated to around 6,000 degrees centigrade produce visible light, while only infrared (invisible thermal radiation) is produced by the sunspots at 2,000 degrees centigrade. Hence the spots are completely dark compared to rest of the extremely bright surface of the Sun.

Sunspots are areas through which extremely high magnetic field comes out and re-enters at another sunspot; comparable to the field lines in an ordinary magnet from north to south poles. The fast moving positively charged hydrogen and helium nuclei, stripped of electrons (known as plasma), produce the magnetic fields in the Sun.

The Sun’s energy is first produced at its centre which is at more than 10 million degrees centigrade and at extremely high pressure. Under these conditions, nuclear fusion of hydrogen and helium nuclei produces extremely high energy gamma radiation. These rays take several thousand years to pass through the dense core of the Sun. This causes the gamma rays to degenerate into low energy visible light that shines out from the Sun and gives life to Earth.

The energy of the fast moving plasma is normally confined within the magnetic field lines that connect from one sunspot to the other. However, when the energy is extremely high, the field lines break, throwing out Sun’s material out into space at great speeds, some close to the speed of light. This solar material consists of subatomic and sub-nuclear particles grouped as cosmic rays. Such explosions on the Sun are known as coronal mass ejections or CMEs (see picture).

CMEs are very harmful to humans but fortunately we are protected from these cosmic particles by the Earth’s own magnetic field. The magnetic envelope deflects the cosmic particles towards the north and south poles which results in a night glow called aurora. When CMEs are aimed directly at Earth some cosmic particles can penetrate the magnetic envelope and harm electronic systems of orbiting spacecraft as well as electrical and electronic systems on the ground.

The current increase in the number of sunspots after several years of quiet is expected to produce much higher energy CMEs that can be even more harmful to the increasing number of communications and research spacecraft as well as our modern lifestyle, which depends on electricity and electronics.

To counter this threat, a new field study called “space weather” has been introduced to understand, monitor, and predict the activity of the Sun. Since the Sun rotates about once every 25 days, sunspots also shift and their numbers and positions change continuously. To know the current status of the Sun you can check the NASA website www.spaceweather.com which is regularly updated.

This month’s night skies hold some interesting views, with crisp, clear skies, rain-free since the beginning of the year. Two planets, Saturn and Mars can be seen overhead in the early evening around 8 pm in the Virgo (the virgin) constellation and close to its brightest star Spica. The two planets show their true nature of being wanderer as they shift slowly across the stationary background stars. Saturn, being far from the Sun, does not show noticeable movement but Mars, being closer to the Sun, moves faster and shifts its position day by day approaching Saturn and Spica. The three will be close together and in line by August 14. Through at telescope, Saturn shows off its beautiful set of flat rings that surround the planet since the ring plane is tilted towards us.

The early morning sky also offers a lot of interesting stars, worth waking up for. Two planets, Jupiter and Venus shine as very bright stars close to each other half way up the sky at sunrise close to the red giant star Aldebaran in Taurus (the bull) constellation, near the Pleiades star cluster. The shift of the planets is quite noticeable as Venus moves away day by day from the Jupiter-Aldebaran pair. The majestic Orion (the hunter) constellation rises below the planet pair. Through a telescope, Venus appears as a crescent since its orbit is inside that of the Earth we can view both its dark and bright sides.

The New Moon on July 19 will have ushered in the holy month of Ramadhan by Saturday 21 after the sighting of a sufficiently high Moon in the bright western skies after soon after sunset. Quarter phase with a half Moon shape will be seen on June 27. This is the time that is most suitable viewing the Moon’s craters because of the long shadows cast at day-night boundary. Full Moon will be on August 3rd while the next New Moon that will be on August 17 will be just at the limit of viewing by August 18, which can mark the end of Ramadhan.

The southern skies are filled with very bright stars that would be hard to hide! The north and south direction pointers, that is the Big Dipper and the Southern Cross, are still high enough in the evening skies and can be used to mark the north-south direction very well. Scorpio in the dominant constellation this month, occupying the overhead evening sky with its three stars forming its tentacles, the red star Antares in its neck and a long winding tail that ends in a close pair forming the sting. Scorpio is the only constellation that does full justice to its namesake, the scorpion and is unmistakable to even a casual stargazer. Use this opportunity to start (or continue) your stargazing hobby by independently identifying a constellation! Below Scorpius, try to identify Sagittarius (the archer). This constellation marks the direction of the center of our Milky Way galaxy and you will notice dense concentration of stars here. The band marking the Milky Way contains numerous stars and dust patches and stretches from the southwest, passing through the Southern Cross and Sagittarius and up to Cygnus (the swan) in the northeast. Leo (the lion) with its distinctive inverted question mark head is low in the western horizon and will be lost after this month.

Among the brightest stars noticeable in the July skies are: Alpha and Beta Centauri in the south form the pair that points continuously towards the Southern Cross; the fourth brightest star Arcturus is overhead towards the north and the fifth brightest star Vega rises in the northeast. Other bright stars you will easily notice are Altair which rises in the east and Spica, the brightest star in the Virgo constellation can be seen almost overhead towards the west.

Among the visible satellites, we will have a clear view of the newly installed Chines space station Tiangong on August 18 when it crosses right across the exact middle of the sky from rising in the southwest at 6:39 pm, reaching maximum altitude at 6:42 pm and setting in the northeast at 6:45 pm having taken 6 minutes to cross the sky from horizon to horizon. For the ISS it is best to consult the website www.heavens-above.com nearer to August 4 when it will also cross the sky from about 7:06 pm in the southwest and setting 7 minutes later at around 7:13 pm in the northeast. Visit the website www.astronomyintanzania.or.tz for more details and information about astronomy in Tanzania.

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